Republican Senator John McCain has not stepped foot in the Capitol this year. His brain cancer treatment and related health problems have kept him back home in Arizona. NPR congressional correspondent Susan Davis reports McCain's absence is weighing heavily on the Senate this month.

SUSAN DAVIS, BYLINE: Even 2,000 miles away from Washington, John McCain can still make news. In a statement, he announced his opposition to CIA director nominee Gina Haspel, saying her refusal to acknowledge torture's immorality is disqualifying. As the Senate's moral authority on the topic, McCain's call to reject her is affecting the calculation on whether or not the nomination can survive.

JEFF FLAKE: Oh, I obviously share his views on torture, and I always have. So his views mean a lot.

DAVIS: That's McCain's fellow Arizona Republican senator, Jeff Flake. He's undecided on Haspel, and McCain's opposition is a factor in his own decision-making. Maine Independent Senator Angus King is with McCain in opposition to Haspel. He said McCain can still influence Senate debate from afar.

ANGUS KING: It may be if he were here personally perhaps he could be talking to some of his colleagues directly. But his statement was so clear. It was hard to miss the point that he made.

DAVIS: Even senators who support Haspel's nomination, like Louisiana Republican John Kennedy, said they still weigh McCain's point of view in these debates.

JOHN KENNEDY: Look; when John McCain talks, I listen. Sometimes I agree with him, sometimes I don't, but I always listen.

DAVIS: Later this month, the Senate Armed Services Committee will take up McCain's prized jewel, the annual defense bill that sets the priorities for the Pentagon. McCain is the committee chairman, but he's not expected to return to shepherd the bill through the Senate. The top Democrat on the committee, Rhode Island Senator Jack Reed, said they're moving forward in the same bipartisan manner on defense policy that McCain demanded as chairman.

JACK REED: Because of him we're going to do our best to do the job he would want us to do, which is to make sure we can authorize legislation for the forces and do it in a bipartisan-principled way.

DAVIS: McCain's health is a matter of constant speculation on Capitol Hill. One of his best friends, South Carolina Republican Senator Lindsey Graham, spent two days in Arizona with him earlier this week.

LINDSEY GRAHAM: He's stabilizing. Don't read - don't believe what you read in the paper. I was concerned when I went. I'm thinking now about my next trip. No talking about funerals.

DAVIS: The end of the month is a politically sensitive deadline in Arizona. May 30 is a cutoff to have a special election this year if the Senate seat becomes vacant. After that date, the governor would appoint a senator to serve until a 2020 special election. Graham tamped down on speculation that McCain's health could force him to resign soon, but quipped that they weren't planning his re-election campaign either.

GRAHAM: We're not at 2022 yet, but we're - I'll let you know.

DAVIS: Instead, Graham described McCain as physically recovering and mentally intact, cracking wise as the two bonded over McCain's favorite movie.

GRAHAM: You want to figure out John McCain, watch "The Man Who Shot Liberty Valance." That tells you all you need to know about me and him.

DAVIS: "The Man Who Shot Liberty Valance" is an old Western starring John Wayne and Jimmy Stewart. In it, a legendary senator returns home for a funeral, and a reporter covering the story ultimately realizes the senator's career is built on a myth. The senator has done so much good, the reporter tosses his notes in the fire, choosing not to destroy the image of a popular politician, telling him this...